1. Field of the Invention
The present invention relates to a belt driving device that drives a belt member, and an image forming apparatus that includes the belt driving device and forms an image on a recording material.
2. Description of the Related Art
To deal with various recording materials, an image forming apparatus includes a transfer unit that transfers a toner image formed on an image bearing member such as a photosensitive drum to an intermediate transfer member and then transfers the toner image formed on the intermediate transfer member to a recording material.
Japanese Patent Application Laid-Open No. 2008-26676 discusses an apparatus that includes a non-contact distance sensor facing a detected surface integrated with an arm moving in contact with an end of a belt in a width direction thereof to detect a position of the belt travelling in the width direction thereof. However, such a sensor that can continuously detect the position requires higher costs than a sensor such as a photo-interrupter.
Japanese Patent Application Laid-Open No. 2010-223981 discusses a configuration that a roller for stretching an intermediate transfer belt is inclined to suppress deviation of a travelling intermediate transfer belt in a width direction thereof. The inclination amount of the roller is controlled based on a detection result by a detection unit that detects a position of the intermediate transfer belt. An arm that is moved in contact with an end of the intermediate transfer belt in the width direction is disposed to detect the position of the intermediate transfer belt. Further, a plurality of sensors such as photo-interrupters is disposed along a movement locus of the arm to detect a detected portion provided for the arm.
In such a configuration, all the sensors detect the common detected portion, and the sensors are, therefore, arranged adjacent each other. Thus, if an interval between the sensors is to be narrow for fine detection, the sensors hit each other or space necessary for attaching the sensor cannot be reserved. Thus, the arrangement interval between the sensors cannot be narrowed, so that fine detection cannot be realized.